Planaria
Panaria are mostly small, marine animals that live in fresh water. They also have both female and male organs. Planaria also have a cool feature to them that allows them to regenerate their body parts. They lack a circualtory and respiratory system.
Planaria are the one of most simple creatures to develop a nervous system. Their nervous system consists of ganglia under the eyes and a cord of nerves that run down the body, under the ventral nerve cord. The planaria ganglia can be called their brain. The three pairs of ganglia under the eyes make a inverted U shape that have nerves sticking out to the outside of the head so that the head of the planarian is more sensitive than the rest of the body. If the light hits the planaria near the eyespots, they will usually move away into darker water making them sensitive ti light.
Planaria are the one of most simple creatures to develop a nervous system. Their nervous system consists of ganglia under the eyes and a cord of nerves that run down the body, under the ventral nerve cord. The planaria ganglia can be called their brain. The three pairs of ganglia under the eyes make a inverted U shape that have nerves sticking out to the outside of the head so that the head of the planarian is more sensitive than the rest of the body. If the light hits the planaria near the eyespots, they will usually move away into darker water making them sensitive ti light.